1. Field
The disclosed and claimed concept relates generally to keypads for handheld electronic devices and, more particularly, to a lighted piano-style keypad.
2. Background Information
Numerous types of handheld electronic devices are known. Examples of such handheld electronic devices include, for instance, personal data assistants (PDAs), handheld computers, two-way pagers, cellular telephones, and the like. Many handheld electronic devices also feature a wireless communication capability, although many such handheld electronic devices are stand-alone devices that are functional without communication with other devices.
Such handheld electronic devices are generally intended to be portable, and thus are of a relatively compact configuration. Piano-style keypads typically provide keys that have very little space therebetween and derive their name from the keys of a piano, which typically are disposed very closely adjacent one another with an extremely small space therebetween. Piano-style keypads provide relatively greater numbers of usable keys in relatively smaller spaces compared with conventionally-spaced keypads due to the very close spacing of the keys of a piano-style keypad. While such piano-style keypads have been generally effective for their intended purposes, such piano-style keypads have not been without limitation.
Piano-style keypads typically comprise a number of key bodies disposed on a resilient web, and further comprise key caps adhered to the key bodies. The web is deflectable to allow a key body to be translated slightly toward a handheld electronic device when a key is being actuated. While the key bodies are typically spaced apart from one another on the web, the key caps that are adhered to the key bodies typically are disposed very close to one another with minimal space therebetween, thus providing the “piano-style” aspect to the keypad.
A number of competing factors typically bear upon the ultimate design of a piano-style keypad. For instance, in order to provide long term reliability of the key caps adhered to the key bodies, each key body typically must have an exterior surface with at least about fifteen square millimeters of adherable area for adhering of the key caps to the key bodies. Additionally, the portion of the resilient web that is peripheral to a key body and that is deflectable when a key body is being translated toward the handheld electronic device desirably has a radial length, i.e., a length in a direction pointed away from the key body in the plane of the web, of at least 0.6 millimeters. Such a length has been determined to provide long term reliability while allowing the key bodies to be easily actuated and to provide a desirable tactile response during such actuation.
Some previous keypads have provided a light guide and key bodies formed as a single component that is molded in a multi-step process. The light guide would be formed from a light-transmitting material, such as a clear plastic. The light guide would then be positioned in a mold, and uncured resilient material would be poured into the mold in contact with the light guide. The resilient material would cure, thus providing resilient structures and key bodies molded to the light guide. However, the size of the resilient structures was limited by the size of the light guide. That is, for a given space, the larger the light guide was, the relatively smaller would be the resilient structures and key bodies molded to the light guide.
As the number of piano-style keys within a given area increases, the adherable surface area of the key bodies and/or the radial length of the web peripheral to the key bodies must decrease, but can only be decreased to a certain extent and cannot be smaller than the aforementioned dimensions. As such, piano-style keypads of a particular size could have only a limited number of keys. It thus would be desirable to provide an improved piano-style keypad that overcomes or at least partially alleviates such limitations.
Similar numerals refer to similar parts throughout the specification.